Equatorial polishing generator



Feb. 19, 1952 A. J. HOLMAN 2 586 334 EQUATORIAL POLISHING GENERATOR Filed April 2, 1947 3 Sheets-Sheet l Feb. 19, 1952 J, HOLMAN 2,586,334

I EQUATORIAL POLISHING GENERATOR Filed April 2, 1947 3 Sheets-Sheet 2 Feb. 19, 1952 A. J. HOLMAN EQUATORIAL POLISHING GENERATOR Filed April 2, 1947 s Sheets-Sheet s Patented Feb. 19, 1952 UNITED STATES PATENT OFFICE 2,586,334 EQUATORIAL POLISHING GENERATOR Arthur J. Holman, Brighton, N. Y.

Application April 2, 1947, Serial No. 739,011

My invention relates to apparatus for polishing curved surfaces on glass or other materials and more especially to precision generator polishing of lens blanks mounted in multiple on a spherical carrier, the exposed surfaces of which have been finish ground to a curved surface common to all in an equatorial diamond milling generator such as I have described in my copending patent application Serial No. 727,244, filed February 7, 1947, now abandoned. The present device is entirely new and is designed to receive spherical carriers as they come from diamond milling generators and to polish quickly, by generating action, the exposed ground surfaces of lens blanks which have been ground to a curved surface common to all. As stated in the above mentioned copending patent application, this invention supplements the equatorial diamond milling generator invention, the two inventions com-, bined providing the most effective method and means for generating precision optical surfaces in large quantities.

The principal object of the present invention is to provide an equipment and a method of procedure to polish, by generating action, the finish ground surfaces of lens blanks mounted in multiple on a spherical carrier thereby effectuating the complete processing of optical surfaces, including rough and finish grinding, also polishing, by the equatorial generating system, which requires that each lens blank be mounted on a spherical carrier but twice for the complete processing of both of its refracting surfaces.

The second object of this invention is to provide a mechanism wherein the spherical carrier may be suitably cradled, the polisher unit may embrace (encircle) the spherical carrier and op-' erate effectively on the ground surfaces of all lens blanks mounted thereon, and the polisher unit and the cradle may be opened easily and quickly for inserting and removing spherical carriers.

Another object of this invention is to provide combined rotation and oscillation of the spherical carrier, also of the polisher unit, the surface of the spherical carrier and the surface of the polisher unit moving at right angles each to the other.

A further object is to provide means whereby the ratio of rotation to oscillation may be varied, both for the spherical carrier and for the polisher unit. c

A further object of this invention is to arrange the polishing elements in a balanced unit which v24 Claims.

is adjustable (1) with respect to pressure of the polishing elements .upon the surfaces of all lens blanks mounted on the spherical carrier, (2) also with respect to pressure of the polishing elements on those lens blanks on the spherical carrier positioned, respectively, above and below its equator.

A further object is to make the polishing elements quickly and easily removable as a unit so the polishing elements may be resurfaced with polishing material and molded to required form before being inserted in the polishing generator.

Further objects are .to provide aligning and locking means whereby the cradle may be correctly and substantially supported; universal mounting for the polisher unit so the polishing elements may be fed continuously and automatically to the lens blanks under pressure equalized over all lens blanks; and gear driving mechanism to cause automatic generating movements of both the spherical carrier and the polisher unit.

Still another object of this invention is to provide a simple and effective means whereby toric surfaces, previously generator milled in multiple on suitable spherical carriers, may be polished on the same carriers without appreciable deviation from the toric form as ground.

The ultimate object of this invention is the complete development of the equatorial generating method for rapid production of lens surfaces whereby lens blanks, mounted in multiple on a spherical carrier and previously fine ground to a curved surface common to all, may be polished quickly and accurately without departure from the true curvature as ground.

The outstanding superiority of the equatorial method for rapid production of precision lens surfaces in large quantities is'due, primarily, to the fact that the surfaces of lens blanks, mounted in multiple on a spherical carrier, may be ground with the greatest accuracy-to a common curvature because the forces acting on the carrier, during the grinding operation, are balanced and hence, vibration and other disturbing influences are eliminated; moreover, since each lens blank surface, as ground, is part of the curved surface common to all lens blanks, the polishing elements arranged in a balanced unit, as hereinafter more fully described, may surround (encircle) the spherical carrier and operate most effectively on the ground surfaces. As a result, polishing is completed in to of the time ordinarily required in spindle polishing machines and, since the polishing is done by generating action, the yield of first quality product should never fall below 95 percent whereas, yield of first quality product on spindle polishing machines, currently in use, is seldom over 50 percent and often is as low as 40 percent. The equatorial generating system permits the mounting of 100 to 150 percent more lens blanks than can be ground and polished successfully on a polar cap grinding and polishing shell. The over all result is about 8 to 1 in favor of the equatorial generating system for large volume production of precision curved surfaces.

My device and the method of its operation may be best understood by reference to the drawings in which:

Fig. 1 is an elevation, at quarter scale, of the complete machine.

Fig. 2 is a plan view, at quarter scale, of the complete machine.

Fig. 3 is an end view, at quarter scale, of the complete machine.

Fig. 4 is a partial vertical cross section, at full scale, on line 4 of Fig. 2 through part of the polisher unit.

Fig. 5 is a partial vertical cross section, at full scale, on line 55 of Fig. 2 through the hinged joint of the polisher unit.

Fig. 6 is a partial vertical cross section, at half scale, on line 66 of Fig. 2.

Fig. '7 is a plan view, at half scale, of a crank disc.

Fig. 8 is a plan view, at half scale, partly in cross section showing arrangement of mechanism for polishing toric surfaces.

Referring now more specifically to the drawings, in which like reference numerals indicate like parts, a base I (Figs. 1 2, 3 and 6) of heavy cast metal has at one end a pair of integral bo ses 2 in aligned bores wherein is snugly fitted hinge pin 3. A cradle 4 comprising a lower portion 5 and an upper portion 6 splits in two at the equator. Lo er portion 5 of the cradle has an integral pro ecting part carrying a pair of aligned bosses I which are bored to fit closely on hinge pin 3 and a pair of spacing collars 8 on hinge pin 3 serve to center lower portion 5 of the cradle between bosses 2 on base I. Also integral with lower portion 5 of the cradle is a pair of aligned bosses 9 in threaded bores wherein are screwed the t readed ends (not shown) of hinge pins l0. Upper portion 6 of the cradle carries a pair of integral projecting arms H and bosses l2 at the ends of arms H are bored to =fit closely on hinge pins l0, thus hingedly connecting lower portion 5 and upper portion 6 of cradle 4. The base I has a turned seat wherein is fitted lower half l3 of a hinged cradle clamping ring which is secured to base I by suitable screws 14. The upper half l5 of the cradle clamping ring is provided, at one end, with a hinge piece [6 and, at the other end, with a suitable clamping device I1 whereby the cradle clamping ring may be drawn down tightly on its turned seat which is continuous on upper portion 6 and lower portion 5 of cradle 4, thus serving to align the portions of the cradle with respect to each gtherI and also to align cradle 4 with respect to ase Cradle 4 is provided with a pair of polar conical journal boxes l8 which are aligned accurately and fitted securely in upper portion 6 and lower portion 5 of the cradle and in these are journaled spherical carrier I9 with its equatorial gear 20. The spherical carrier and its structure are described fully and claimed in the copending patent application hereinbefore referred to and reference is hereby made thereto for details regarding structure of the spherical carrier. The spherical carrier actuating shaft 2!, journaled in suitable bushings press fitted in a bore in integral projecting part of lower portion 5 of the cradle, carries fixed on one end a gear 22 which meshes accurately withand drives equatorial gear 20 on spherical carrier l9, and on the other end of shaft 2| is secured a gear 23.

The base I is provided adjacent the end opposite integral bosses 2 with two sets of integral machined bosses whereon are securely supported and accurately aligned bearing brackets 24 and 25 each of which houses a precision cylindrical roller bearing and in these are journaled the hollow shaft 26. In suitable bushings press fitted in the bore of hollow shaft 26 is journaled cradle alignment rod 21 accurately threaded at one end to fit into a threaded bore which is half in lower portion 5 and half in upper portion 6 of cradle 4 '(Fig. 6).' A clamp ring 28, having a hub accurately fitted on and secured to cradle alignment rod 21, contains a bore slightly beveled at its edge which fits with slight clearance over a tim jecting boss on cradle 4. On the outboard end of cradle alignment rod 21 is pinned hand wheel 29 (Figs. 1 and 2) by means of which cradle alignment rod 2'! may be turned, in one direction, so that clamp ring 28 is forced over the projecting boss on cradle 4 thereby locking securely together lower portion 5 and upper partion 6 of cradle 4 and also serving further to align cradle 4 with respect to shaft 25. By turning hand wheel 29 in the opposite direction, clamp ring 28 is withdrawn from the projecting boss on cradle 4, thereby unlocking the portions 5 and 6 of the cradle at this point. The end of hollow shaft 26 is recessed to provide clearance for clamp ring 28 so that'the threaded end of cradle alignment rod 2'! may be withdrawn com- ,pletely from lower portion 5 of cradle l.

A steel collar 30 (Fig. 6), shrunk on the end portion of hollow shaft 25, is provided with aligned threaded bores at opposite ends of one diameter wherein threaded hinge pins 3! are snugly fitted. Collar 30 is provided with exterior parallel faces surrounding the threaded bores 'whereon is seated gimbal ring 32 in bores wherein hinge pins 31 fit with rrinimum clearance. On a diameter at right angles to the axis of hinge pins 31, gimbal ring 32 (Figs. 1 and 2) is provided with a pair of threaded bores wherein threaded hinge pins 33 are snugly fitted. Surrounding these threaded bores in gimbal ring 32 is a pair of parallel faces equally spaced from the axis of hollow shaft 25 and against these faces are seated the inner faces of bosses 33 which ere;

integral with end ring 35. Bosses 34 project from one face of end ring 35 at opposite ends of a diameter thereof and contain aligned bores which fit with minimum clearance on hinge pins 33. The collar 30, shrunk on hollow shaft 25, hinge pins 3|, gimbal ring 32, hinge pins 33 and end ring 35 constitute a universal joint whereby end ring 35 may be driven by shaft 25 but end ring 35 may assume, freely, positions wherein its: axis will not be coincident with the axis of hollow' shaft 26.

Integral with end ring 35 and projecting from. the face thereof opposite bosses 34, are a pair of bosses 36 (Figs. 1, 2, 4 and 5) which are bored to press fit on the enlarged ends 3! (Fig. 5) ofpolisher unit drive pins 33 the axes of which are parallel to the axis of end ring 35, lie in the same plane as the agris of end ring 35 and are equally t p-a ed ther fre a The o isher uni s energis d o ,a we half .3 and an ar er half hisk ar identica as en h t t e er a was an 0 up e half 40 is 9 sees s s e i H h urpose h einafte e ais he ha c the polisher unit are hinged together at ene end as h aring bu hin 4| which s pr f t s in the here in upper half 40 and is a good turning fit in the bore in lower half 39. On the opposite side ef the polisher unit, bearing bushing 42 is press fitted in the bore in the end of lower half 39, and the bore in the end of upper half 40 is notched out so it may slide freely over bearing bushing 42 as the free ends of the halves of the polisher unit come together through swinging of the halves .on hinge bushing 4|. The halves of the polisher unit are lined with suitable lens polishing material 43 which may be molded to the required form and thickness in a suitable fixture before the polisher unit is inserted in the machine. The bores in bearing bushings 4i and 42 slide freely over polisher unit drive'pins 38 which are a good fit therein.

To minimize distortion of the halves of the polisher unit under pressure applied by the polisher to the ground lens surfaces to be polished, I have arranged to apply clamping pressure on the polishing unit at points spaced 120 degrees apart around the circumference of the polisher unit. A hinge pin 44 (Fig. 3) supported at both ends in the flanges integral with lower half 39 of the polisher unit, is spaced 120 degrees from bearing bushin'g whereon the halves of the polisher'unit are hinged together: a hinge pin 45 (Figs. 2 and 3) is supported in like man:- ner in upper half 40 of the polisher unit and is also spaced 120 degrees from bearing bushing 4|. n bow spring member 46, hingedly attached to lower half 39 of the polisher unit by hinge pin 44, carries hingedly mounted at its upper end a member 4'! which may he slipped over hinge pin 45 by deflecting bow spring'member 46 inwardly and, when so positioned, bowspring member 45 presses bot-h halves of the polisher unit toward each other, thereby applying the polishing material 43 under pressure to the ground surfaces of lens blanks mounted on spherical carrier [9. To regulate the pressure of the polishing material against the lens blanks,

I have provided at the lower end of member 4! a a hingedly connected screw member 48 which projects through a hole in how spring member 45 and is provided with an adjusting nut 49 whereby the tension in bow spring member 46 may be increased or decreasedas' desired. By screwing adjusting nut 49 further on screw member 48, the tension in bow spring member 46 is increased and the pressure of the polisher unit against the lens blanks is increased: by backing ofi adjusting nut 49, pressure of the polisher unit against the lens blanks is decreased.

From the foregoing description of the polisher unit and its universal mounting on hollow shaft 28, it is obvious that there is considerable overhung weight in these parts which will rest on the work mounted on the spherical carrier and the extra pressure will come, naturally, on those lens blanks which are positioned on the spherical carrier above diametral gear 20. If no provision is made to carry this overhung weight,

the lens surfaces on the carrier positioned above diametral gear 20 will polish out sooner than the lens surfaces positioned below diametral gear 20. To carry this overhung weight and thereby equalize the pressure applied by the will icxa swi s lei-i su acerso th carrie I19 I have nwvi ed the ellewie eehee m; selle 5!! Fi s- 3 n 6 l' d 'l-l ilPWPQl a a ns 1 1. uter Per r f end i .35 i? QP PEPI Q in ne 3W1 0 an e racket f h ch h n e na n s @11 p n 52 was si d an a ba in b se h la e and, 9 a le bra ket cap a a ar rei .3 lun er 53 fits l Spring un 53 has an enlarged threaded portion 54 which cre i t a ta ped 12 s i b e I a dis id q at it ute nd ith a h x on h d- A @911 as ice 55 s relapsin rin Plunger @Pl Q1 9. 9 e? in t h 19 9 of angle brac et 51 and a th p h and against e en ar ed io 54 f pr n u e B m ans o a su table r c Spring plunger 53 may be screwed further into base I thereby increasing the pressure of coil spring 55 against the lewer end 9; angle bracket 5| and hence, increasing the upward pressure exerted by reller 50 upon end ring 35. When the pressure exerted by roller 50 against end ring ,35 is equivalent to the combined overhung weight of the polisher unit and the universal joint mechanism connecting it with hollow shaft 26, then the pressure applied by the polisher unit to the ground lens surfaces mounted on spherical carrier [9 will be equalized in all zones both above and below equatorial gear 20. If it is found, upon operation of the machine, that lens blanks above the equator of the spherical carrier polish more rapidly than lens blanks below the equator, then spring plunger 53 should be screwed further into base I: if lens blanks below the equator polish more rapidly, then spring plunger 53 should be backed out of the base I till lens blanks above and below the equator of the spherical carrier polish out in the same time.

Before describing in detail the mechanism whereby the polisher unit and the spherical carrier are actuated to perform the polishing op eration, it seems in order to state the nature of the fundamental principles employed, for the first time, in this device for such operation. It will be understood from the foregoing detail description of my device that the spherical carrier, whereon ground lens blanks are mounted, is restricted, in its cradle, to rotation and oscillation about its polar axis. Although the polisher unit is actuated through a universal joint connecting it with hollow shaft 26, nevertheless, the polisher unit, which is hollow and spherically formed surrounds (encircles) the spherical carrier and seats on the spherical surface common to all ground lens blanks and, therefore, is restricted by the very nature of the set up to rotation and oscillation around the spherical carrier, the equator of the polisher unit moving on polar great circles thereon; i. e., great circles which pass through the polar axis whereon the spherical carrier may rotate and oscillate. Since the ground lens surfaces are adjacent the equator of the spherical carrier, and not on its polar cap, it is obvious that rotation of the spherical carrier on its axis does not cause the ground lens.

surfaces to rotate, each on its own individual axis, but rather, rotation of the carrier causes all ground lens surfaces to sweep across the surface of the polisher unit and at right angles to the direction wherein the polisher unit itself has freedom of movement.

It will be observed, from examination of Fig. 6, that if two planes, parallel to the plane of the equator, were cut through the upper edges of compensating factors.

lens blanks mounted above the equator and through the lower edges of lens blanks mounted below the equator, these planes would intersect the spherical surface of the carrier on two circles of equal diameter and the diameter of these circles is about 77 per cent of the equatorial diameter of the spherical carrier. This means that the minimum instantaneous rate of movement of any part of a ground lens surface across the surface of the polisher unit in a direction at right angles to the direction of movement of the polisher is never less, at the same instant, than 77 per cent of the maximum instantaneous rate of movement in the same direction. This is quite different from the situation in polar cap polishing wherein a polar cap shell spins on its own axis and the movement, due to rotation of the shell, of elements of the ground surface on lens blanks, varies from zero on the axis of the shell to the maximum amount at the edge of the shell.

Although the minimum instantaneous rate of movement of the elements of. ground lens surfaces farthest removed from the equator is only 77 per cent of the maximum instantaneous rate, as above defined, this does not mean that elements of the ground lens surfaces lying adjacent the equator will polish out faster. There are several First, since the polisher surface has the same width throughout its circumference, it is obvious that each complete revolution of the spherical carrier causes each element of ground lens surface on the carrier to traverse twice the full width of the polisher surface. In this respect, therefore, every element of ground lens surface on the carrier receives identical treatment from rotation of the spherical carrier on its polar axis.

Since the equator of the polisher unit travels about the spherical carrier on its polar great circles and since the polisher surface is of considerable and uniform width, it is to be noted that those elements of ground lens surface, which have a relatively lower instantaneous rate of movement across the polisher surface from side to side, because they are further removed from the equator of the spherical carrier, will remain longer in contact with the polisher surface: in fact, all elements of ground lens surface on the carrier will remain under the polisher surface for periods inversely proportional to their relative rates of travel across the surface of the polisher from side to side. Thus, whatever decrease in polishing effeet is caused by the lower relative instantaneous rate of movement of ground lens surface across the polisher from side to side, at zones on the carrier removed from its equator, is fully compensated because the polisher surface, moving with its equator always on a polar great circle of the spherical carrier, operates on ground lens surfaces in these zones for proportionately longer periods.

It will be observed further, from examination of Fig. 6, that zones on the surface of the polisher at its edges, i. e., furthest removed from its equator, will travel at a somewhat slower rate across the ground lens surfaces on the carrier: in this case, the minimum instantaneous rate is about 85 per cent of the maximum instantaneous rate, at the same instant. Since all zones on the polisher contact at some time all zones on the ground lens surfaces, it seems evident that the polishing effect over all zones on the spherical carrier is equalized. Moreover, the edge zones of the polisher surface remain proportionately longer in 8 contact with ground lens surfaces on the spherical carrier, for reasons previously described, hence the abrading effect of the ground lens surfaces on the surface of the polisher is equalized. Thus the polisher surface always remains truly spherical.

It appears from the foregoing considerations, that simple rotation of both the spherical carrier and the polisher unit should produce uniform polishing action over all ground lens surfaces on the spherical carrier and also provide even wear on all zones of the polisher surface. It is obvious that, if the spherical carrier and the polisher unit were each rotated at the same rate, a given point on the surface of the polisher would trace, during one half revolution, a diagonal line on the surface of the carrier at an angle of 45 degrees to the plane of its equator and, during the second half revolution, the point on the polisher would trace a second diagonal line on the carrier at right angles to the first line traced, thus formin an X: succeeding revolutions would trace merely superimposed Xs. This condition does not represent good lens making practice because any irregularity, either in the surface of the polisher or in the ground lens surfaces, would track on the other surface and hence, would form a pattern. To avoid this condition in my equatorial polishing generator, I have combined rotation with oscillation in actuating both the spherical carrier and the polisher unit. Adjustments may be made selectively, in the oscillating mechanism, to provide rotation, during each oscillation cycle, through an angle of 10 to 25 per cent of the angle of oscillation. Since, in each case, rotation and oscillation must take place about one and the same axis, it is necessary to combine these two movements by superimposing them on polisher unit actuating shaft 28 and also on spherical carrier actuating shaft 2i. This can be accomplished most effectively through use of a differential gear train in each actuating mechanism by (1) rotating continuously the ring gear of the differential, (2) oscillating one in-line shaft about its own axis, and (3) gearing the other in-line shaft directly, in one case, to polisher unit actuating shaft 26, and, in the other case, to spherical carrier actuating shaft 2 l.

The gear train for operating my device is shown, diagrammatically, in broken lines in Figs. 1, 2 and 3 and a differential mechanism is shown partly in section in Fig. 6. Main drive pulley 56 is fixed on the end of shaft 51 and on the other end thereof is fixed worm 58 which drives worm gear 59 fixed on transverse shaft fill. A helical gear 6|, fixed on shaft 60, meshes with and drives helical gear 62 fixed on crank shaft 63. A crank disc 64 (Figs. 1, 2 and 7) is keyed to and shrunk on one end of crank shaft 63 and a threaded crank pin 65 may be screwed into any selected tapped hole in crank disc 64 to provide the desired amount of crank throw. A connecting rod 66 is adjustably attached at one end to crank disc 64 by crank pin 65 and at the other end to oscillating arm 61 by a threaded bearin pin 58 similar to crank pin 65. Oscillating arm G7 is keyed on oscillating shaft 69 which is one of the in-line shafts in the differential mechanism enclosed in differential housing 70. A spur gear H, also fixed on transverse shaft 60, meshes with and drives a gear 72 fixed on shaft 13. A spur gear M, fixed on shaft 13, meshes with and drives a gear '15 fixed on shaft 76. A worm 11, also fixed on shaft 16, meshes with and drives ring gear 18 of the differential mechanism enclosed in differential housing I0.

Power is fed to the second differential mechanism in the following manner: A spur gear I9, fixed on the end of transverse shaft "60, meshes with and drives gear 80 (Figs. 1, 2 and 3) fixed on crank shaft SI. A crank disc 82, like crank disc 64, is keyed to and shrunk on one end of crank shaft 8| and a threaded crank pin 83, like crank pin 55, may be screwed into any selected tapped hole in crank disc 82 to provide the desired amount of crank throw. A connecting rod 84 is adjustably attached at one end to crankdise '82 by crank pin 83 and at the other end to oscillating arm 85 by a threaded bearing pin 86. Oscillating arm 85 is keyed on oscillating shaft it! which one of the in-line shafts in the differen fal mechanism enclosed in differential housing 88, A spur gear 89, also fixed on transverse shaft 61!, meshes with and drives a gear 2 9 fixed on shaft St. A helical gear 92, also fixed on shaft 9 l,-rneshes with and drives helical gear 93 fixed on shaft 9 4. A worm 95, fixed on shaft 94, meshes with and drives ring gear 95 of the differential mechanism enclosed in differential housing 88.

Differential housing 70 encloses and supports a differential gear mechanism in the following manner: Bearing rings 91 and 98, fitted in suitable bores turned in difierential housing H3, journal in suitable antifriction bushings revolving yoke 99 whereon differential ring gear "I8 isseat'e'd and retained in position by suitable screws. A shaft I053, fitted accurately and pinned in a pair of diametrically opposite bores in revolving yoke 99, the common axis of which bores intersects Lat i right angle the axis,.extended, of in-line oscillating shaft 69, supports rotatablyon suitable antifriction bushings a pair of identical spiral bevel gears lfll. An ,antifriction bushing 102 surrounds shaft I and spaces properly the spiral, bevel gears IUI. A spiral bevel gear I93, meshing accurately with spiral bevel gears IOI and keyed on the enlarged portion of oscillating shaft 69, is journaled in an antifriction bushing I 04 which also journals one side of yoke 99 and the hub of oscillating arm 6-? and is itself press fitted in cover plate I of differential housing -10. Cove-r plate H is retained in position by suitable screws and serves to position properly bearing rings -9 "I and 98 Within differential housing -10. A projecting boss IE5, integral with cover plate H35, has

a machined seat whereon is held bysuitable screws;

a part I 97 wherein the outboard end of oscillating shaft 89 is suitably journaled in an antifriction bushing. A spiral bevel gear [08, exactly like spiral bevel gear I93, meshes accurately with spiral bevel gears In! and is keyedon shaft 109 journaled in an antifriction bushing III) which fits snugly in the bore in one side.of.yoke.-99. .A spur gear H I, keyed also on shaft I09,.has a hub which is journaled in bushing .LIB. The-end portion of shaft m9, of reduced diameter, isljounnaled in an antifriction bushing pressgfittediin a bore in the end of differential housing :10. Gear III, having combined rotating and oscillating movement, meshes with and .drives gear :23 .on spherical carrier actuating shaft 2 I.

An identical differential gear mechanism enclosed and supported in differential housing 88, receives a continuous rotative impulse through ring gear'tt (Figs. 1 and 3) and an oscillative impulse through in-line oscillating shaft .81 (Fig. 3) as hereinbefore described, and combines these impulses in spur gear I I2 (Figs. 1, 2 and 3) which is fixed on the second in-line shaftin this differ- 10 ential mechanism opposite to in-line oscillating shaft 81. Spur gear H2 meshes with anddrives gear [I3 fixed on hollow shaft 26 which is the polisher unit actuating shaft. A housing II 4 (Fig. 2) encloses gear H3.

Power applied through V belts to main drive pulley 56 operates the entire mechanism through the-gear train described in detail herei-nbefore. To secure the best polishing action from this generator, it is recommended that the crank drives to the oscillating mechanisms be so set with respect to each other, by proper initial meshing of driving gears in assembling the mechanism, that oscillating arm $5 is atone end of its swing stroke when oscillating arm B'I is at the middle of its swing stroke. When the crank movements are so related, the oscillating motions of the polisher unit and the spherical carrier, combined at right angles, will be 90 degrees out of phase with respect. to each otherr As a result, any given point on the surface of the polisher will move in a circular path over the surface of the spherical carrier. Since the gear ratiosare -l to 1 from the output gears of the'diiferential mechani'sms to both the polisher unit and the spherical carrier, the diameter of the circular path, upon the spherical carrier, of a given point'on the surface of the polisher, will be equal to the cord which subtends an angle at the center of the spherical carrier equal to the angle through which oscillating arms 67 and 85 are swung by their respective crank mechanisms. This condition obtains when the adjustably mounted crank pins are positioned so each crank has the same throw. If crank throws are not equal, .the path will be elliptical instead of circular. Because of continuous slow rotation of both the polisher unit and spherical car rier, successiv e circular paths will not superimpose but will be spaced uniformly around the surface of the spherical carrier. Moreover, when the circular path is scribed in a clockwise direction on the surface of the spherical carrier on one side thereof, it will be scribed in ,a counter clockwise direction on the opposite side ofthe carrier.

After suitable polishing material has been molded in the halves of the polisher unit, the polisher unit may be insertedin the machine'in the following manner: Hand wheel 2,9'is turned toscljew cradle alignment rod 21 out of cradle .4

and thus withdraw clampring 28 (Fig. 6) from around the projecting bosses .on upper portiont and lower portion 5 of. the cradle. Clampingdevice I I is 'released and .theupper half'l5 of the c adle clamping firing ifsswung open on hinge piece I6, thus freeing cradle 4' so it may swing'to the ri ht (Fig. 6,) ,on cradlehinge 3, Where it may rest on ,top of dilferential'housing By unscrewingthreadedhing'e pins 33 from gimbalring 32 (Fig. 1),, end ring ,35 be withdrawn from themachin'e. The polisher unit may then be slipped'on over'driving pins 38 (Figs. .4 and 5) which are press fitted in' end 'ring 55. End ring as with the polisher unitthus mounted thereon,

' may 'th lnbe' put ack-in ositio i themachi kne ded in p n .3 crewed back into be rin and th p sher unit iiD plac Farms-e t equine rfor pqlishine rou d cn fsu c s on a spherical carrier, the-proce-v ur isas fcl pws By pul in onthe upper end of memb -4. KiE'ig. 3 it will ecom.e disen a d from hin e :pin 45, and .;bow spring member r45 will iSWiI g outwardly .,s0 lthat upper :half .41! of.

thepolisher. unit may swingon. hinge v:bu'shing 4 I till itrests 0111301301 base I. CradleJLmay then ll be swung on hinge pin 3 till-the cradle rests on lower half l3 of the cradle clamping ring (Fig. 6). Upper portion 6 of the cradle is swung back on hinge pin so that spherical carrier [9 may be dropped gently into position in lower portion 5 of the cradle. Upper portion 6 of the cradle is then swung back into closed position, upper half l5 of the cradle clamping ring is returned to closed position and locked by clamping device ll, and hand wheel 29 is turned to screw cradle alignment rod 21 into the end of cradle 4 thus drawing clamp ring 28 around the projecting bosses on cradle 4 and locking the cradle portions securely to each other and in alignment with polisher actuating shaft 26. Upper half 40 of the polisher unit is swung back over the cradle and bow spring member 46 is snapped back into operating position over hinge pin 45. Tension on bow spring member 46 is adjusted, by means of adjusting nut 49, to give the desired pressure of the polishing material 43 against the ground lens surfaces on spherical carrier 19. The machine is then loaded and ready for operation and power is turned on to drive the operating mechanism. l-olishing continues until the lens surfaces are completely polished.

The polishing material 43 forming the lining of the polisher unit is, preferably, of such composition and of such porosity that it will retain sufficient moisture to polish out the ground lens surfaces on several spherical carriers. The particular polishing oxides used are part of the composition, either in the form of buttons distributed over the polisher surface or as small particles distributed generally throughout the composition. If desirable, the composition may be moistened with suitable fluid as each spherical carrier is loaded into the machine or fluid may be added, from time to time, while the machine is in operation by using an atomizer.

With the lens surfaces properly ground in my improved equatorial diamond milling generator, all lens surfaces on a spherical carrier should be completely polished in eight minutes, or less, so the complete polishing cycle, including unloading and reloading spherical carriers in the cradle, should not exceed ten minutes. Thus, each polishing machine should polish the ground lens surfaces on at least six spherical carriers each hour. With 16 six curve lenses mounted on each spherical carrier, the production of polished lens surfaces should approach very closely to 100 per hour for each polishing machine. An efficient operator should have no difliculty tendingfour polishing machines and hence, should turn out something like 400 polished lens surfaces per hour.

A polishing generator for toric surfaces mounted in multiple on a spherical carrier and ground in the manner specified in my copending patent application hereinbefore referred to, is somewhat difierent in structure from the spherical lens polishing generator. In Fig. 8 I have shown a plan view of a modified set up suitable for polishing ground toric lenses mounted in multiple on a spherical carrier. In such a device, the universal mounting of the polisher unit is dispensed with and the polisher unit, comprising a hollow hemispherical shell H5 supporting a suitable composition polishing ring H6 within a bore adjacent its open end, is press fitted directlyon polisher actuating shaft 26. Instead of cradle ll'l being hinged to the base on a hinge pin positioned parallel to the top of the base, as

in the spherical polishing generator, it is hinged to the base on hinge pin H8 standing vertical to 12 the top of the base so the cradle may be swung in and out of the polishing ring on a vertical axis. A boss H9, integral with the machine base, has a threaded bore wherein stop screw I is adjustably mounted to contact a boss l2l on cradle Ill and thus limit the movement of cradle ll'l toward polishing ring H6. Toric ground lens surfaces on the spherical carrier I22 are pressed against the polishing ring H8 by suitable spring means (not shown) which tends to swing cradle I I! in a counter-clockwise direction around hinge pin H8. Stop screw 120 is adjusted so the polishing ring I 16 makes sufficient contact with the toric ground lens blanks to polish the surfaces. The stop screw prevents the cradle from swinging further toward the polishing ring as the polishing ring loses contact with one toric ground surface and before it makes contact with the next adjacent toric surface on the spherical carrier. Since this method of hinging the cradle to the base does not permit the use of the spherical carrier actuating mechanism hereinbefore described, it is necessary to provide a member I23 to which cradle H! is secured, and which also swings on hinge pin H8. The member I23 supports a differential gear mechanism in differential housing I24, together with suitable gear train and crank means for feeding rotating and oscillating impulses into the differential gear mechanism. It is also advisable to mount, beneath member I23, a separate drive motor for operating the spherical carrier actuating mechanism.

In polishing toric ground surfaces, it is advisable to use a narrow polishing ring HS, its width being somewhat less than one fourth the diameter of a toric lens blank. The structures of the toric surface polishing generator should be so organized that the polar axis of the spherical carrier 122 will lie in the medial plane of the surface of the polishing ring H6: i. e., in the plane lying midway between the sides of the polishing ring. Moreover, the polishing ring must not be permitted to wear appreciably or it will change the curvature of the ground toric surface. The composition of the polishing ring should be such, therefore, as to resist wear, also polishing material should be added frequently to maintain substantially constant curvature on the surface of polishing ring IlG.

The structures I have illustrated and described represent, for the present, the preferred forms of my device. It is to be understood, however, that other mechanisms may be designed and constructed by those skilled in the art, for performing the essential functions of the present structures, namely, equatorial polishing of ground lenses mounted in multiple on a spherical carrier. The attached claims are drawn sufficiently broad to cover any and all devices of this character, also the methods of their use, and it is the intention that the claims be so interpreted.

Having thus fully described my new equatorial polishing generator, also the methods for polishing ground curved surfaces mounted in multiple ona spherical carrier, what I claim is:

1. An equatorial polishing generator, comprising a cradle adapted and arranged to journal a spherical carrier for rotation and oscillation about its polar axis, means for actuating said spherical carrier both as to rotation and oscillation while journaled in said cradle, a polisher unit rotatably mounted adapted and arranged to embrace said spherical carrier while journaled in said cradle and to operate eifectively on ground surfaces of len blanks mounted in multiple onsaid sphericalcarrier, means for actuating said polisher unit both rotatively and oscillatively so its equator will move on polar great circles of said spherical carrier, means for aligning said cradle and saidpolisher unit, and means for operating simultaneously said means for actuating said spherical carrier and said means for actuating said polisher unit.

2. An equatorial polishing generator, comprising a base, a cradle hingedly supported from said base, adapted and arranged to journal a spherical carrier for rotation and oscillation about its polar axis, means for actuating said spherical carrier both as to rotation and oscillation while journ'aled in said cradle, a polisher actuating shaft journaled in bearings supported on said base,- a polisher unit adapted and arranged to embrace said spherical carrier while journaled in said cradle and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier, a flexible joint connecting said polisher unit with said polisher actuating shaft, means for aligning said cradle with said polisher actuating shaft, means for actuating said polisher actuating shaft both rotatively and oscillatively, and means for operating simultaneously said means for actuating said spherical carrier and said means for actuating said polisher actuating shaft.

3. A lens surface polishing machine, comprising a base, a hinged split cradle hingedly supported from said base adapted and arranged to journal a spherical carrier for rotation and oscillation about its polar axis, differential gear means to provide combined rotation and oscillation of said spherical carrier while journaled in said cradle, a polisher actuating shaft journaled in bearings supported on said base, a polisher unit adapted and arranged to embrace said spherical carrier while journaled in said cradle and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier, a universal joint connecting said polisher unit with said polisher actuating shaft, differential gear means to provide combined rotation and oscillation of said polisher actuating shaft, and means for operating simultaneously both differential gear means.

4. A lens surface polishing generator, comprising a base, a cradle split in two parts at its equator and hingedly joined, a pair of polar conical journal boxes in said cradle, said cradle being hingedly supported from said base and adapted to journal a spherical carrier in said polar conical journal boxes, differential gear means to provide combined rotation and oscillation of said spherical carrier while journaled in said cradle, a polisher actuating shaft journaled in bearings supported on said base, a split polisher unit adapted and arranged to embrace said spherical carrier while journaled in said cradle and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier, a universal joint connecting said split polisher unit with said polisher actuating shaft, means for simultaneously locking the parts of said cradle securely together and aligning said cradle with said polisher actuating shaft, means for balancing the overhung weight of said polisher unit and said universal joint, differential gear means to provide combined rotation and oscillation of said polisher actuating shaft, and means for oper-- 5. An equatorial polishing generator for t'oric' Jul surfaces, comprising a cradle adapted andar ranged to journal aspherical carrier for rotation and oscillation about its polar axis, means for actuating said spherical carrier both as to rotation and oscillation While journaled insaid cradle, a polisher unit rotatably mounted adaptedand arranged to embrace said spherical carrier while journaled in said cradle,andto operate effectively on toric ground surfaces oflens blanks mounted .imultiple on said spherical carrier, means for actuating said polisher unit both rotatively and oscillatively so its equator will move on polar great circles of said spherical carrier,- means for aligning said cradle and said polisher unit, and means for operating simultaneously said means for actuating said spherical carrier and said means for actuating said polisher unit.

6. A toric lens surface polishing machine, comprising a base, a hinged split cradle hingedly supported from said base adapted and arranged to journal a spherical carrier for rotation and oscillation about its polar axis, differentialgear means for actuating said spherical carrier both rotatively and oscillatively at the same timeand while journaled in said cradle, a polisher shaft journaled in bearings supported on said base,- a

polisher unit mounted on said shaft adapted and arranged to embrace said spherical carrier while journaled in said cradle and to operate effectively on toric ground surfaces of lenses mounted in multiple on said spherical carrier, differential gear means for actuating said polisher shaft both rotatively and oscillatively at the same time, and means for operating simultaneously both differ ential gear means.

'7. A toric lens surface polishing machine, com prising a base, apolisher shaft J'ournaled in bearings supported on said base, a polisher unitmounted on said shaft comprising a hollow hemispherical shell wherein is suitably supported a narrow equatorial, polishing ring, a cradle adapt-- ed and arranged to journal a spherical carrier for rotation and oscillation about its polar axis, means for actuating said spherical carrier both as to rotation and oscillation while journaled in said cradle, a hinge pin supported from said base and standing vertical thereto whereon said cradle is hingedly mounted so said cradle may swing partially within said equatorial polishing ring to such position that the equator of said polishing ring contacts toric ground surfaces of lens blanks mounted in multiple on said spherical carrier along polar great circles thereof, adjustable stop means for limiting the swing of said cradle within said polishing ring, means for actuating said polisher shaft both asto rotation and oscillation,- and means for operating simultaneously said means for actuating said spherical carrier and said means for actuating said polisher shaft.

8. In a device of the character specified, the combination of a spherical carrier removably journaled in a cradle for rotation and oscillation about its polar axis, differential gear means to provide combined rotation and oscillation of said spherical carrier about its polar axis while jour naled in said cradle, a hollow spherically formed polisher unit adapted and arranged to surround and rotate concentric with said spherical carrier While journaled in said cradle and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier, and means for actuating said polisherunit so its spherical carrier'.-

9; In a deV-ic'e ofthe character specified, the:

combination of a spherical carrier removably journaled in a cradle for rotation on its polar axis, means for actuating said spherical carrier for combined rotation and oscillation about its polar axis, a hollow spherically formed polisher unit adapted and arranged to surround and rotate concentric with said spherical carrier while .iournaled in said cradle, and to operate eifectively on ground surfaces of lens blanks mounted in multiple thereon, and means for actuating said polisher unit so its equator will move on polar great circles of said spherical carrier.

10. In a device of the character specified, the combination of a spherical carrier removably mounted and journaled in a cradle for rotation on its polar axis, means for actuating said spherical carrier, a polisher unit rotatably mounted adapted and arranged to embrace said spherical carrier and to operate effectively on ground surfaces of lens blanks mounted in multiple thereon, and difierential gear means for actuating said polisher unit both rotatively and oscillatively so its equator will move on polar great circles of said spherical carrier.

11. In a lens polishing machine, theconrbination of a spherical carrier removably journaled in a cradle for rotation about its polar axis, differential gear means to provide combined rotation and oscillation of said spherical carrier while journaled in said cradle, a rotatably mounted polisher unit adapted and arranged to embrace said spherical carrier While journaled in said cradle and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier, means for aligning said polisher unit and said cradle, and differential gear means to provide combined rotation and oscillation of said polisher unit, so its equator will move on polar great circles of said spherical carrier.

12. In an equatorial polishing machine, the

combination of a spherical carrier rotatably mounted in a cradle, means for rotating said spherical carrier, a hollow spherically formed polisher unit supported around said spherical carrier for rotation on an axis at right angles to the axis of rotation of said spherical carrier, and means for actuating said polisher unit for combined rotation and oscillation about one axis, said polisher unit being adapted and arranged to surround said spherical carrier and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier.

13. In an equatorial polishing generator, the combination of a spherical carrier journaled in a cradle for rotation on its polar axis, a polisher unit mounted for rotation on its polar axis, said polar axes standing at right angles to each other, said polisher unit being adapted and arranged to embrace said spherical carrier and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier, and a pair of diiferential gear mechanisms adapted and arranged to actuate both rotatively and oscillatively said spherical carrier and said polisher unit.

14. In an equatorial polishing generator, a balanced polisher unit comprising two nearly identical halves hinged together at one end, an antiiriction bushing whereon said halves are hinged, a second antifriction bushing press fitted into a bore in the opposite end of one of said halves, and over which the slotted bore in the end of the other of said halves may slide, said antiiriction bushings being adapted and arranged to slide over polisher unit drive pins, a lining of lens pol- 16 ishing material covering the inner surfaces of said halves, and resilient means hingedly connected with said halves at positions equidistant from said antifriction bushing whereon said halves are hinged and arranged to press the free ends of said halves toward each other.

15. In an equatorial polishing generator, the combination of a polisher actuating shaft rotatably mounted in suitable bearings, a universal joint including an end ring mounted on one end of said shaft, polisher unit drive pins fixedly mounted in said end ring, and a balanced polisher unit slidably mounted on Said drive pins, said polisher unit being adapted and arranged to embrace a spherical carrier and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier.

16. In an equatorial polishing generator, the combination of a polisher actuating shaft rotatably mounted in suitable bearings, a universal joint including an end ring mounted on one end of said shaft, polisher unit drive pins fixedly mounted in said end ring, a balanced polisher unit slidably mounted on said drive pins, and

v adjustable means whereby upward pressure may be applied continuously upon the outer periphery of said end ring to balance the combined overhung weight of said universal joint and said balanced polisher unit, said polisher unit being adapted and arranged to embrace a spherical carrier and to operate effectively on ground surfaces of lens blanks mounted in multiple on said spherical carrier.

17. A lens polishing machine comprising a polisher unit arranged to encircle a spherical carrier at right angles to its equator, means for actuating said polisher unit rotatively, a spherical carrier journaled in a cradle for rotation on its polar axis, and spherical carrier operating means including multiple gear trains, crank mechanism and differential unit, all adapted and arranged to impart to said spherical carrier combined rotation and oscillation about its polar axis.

18. A lens polishing machine comprising a rotatably mounted spherical carrier and its supporting and actuating means, a hollow spherically formed polisher unit arranged to surround said spherical carrier so its equator will move over polar great circles thereon, and polisher unit operating means including multiple gear trains, adjustable crank mechanism and differential unit, all adapted and arranged to impart to said polisher unit combined rotative and amplitudeadjustable oscillative movement about its polar axis.

19. In an equatorial polishing generator, a balanced polisher unit comprising a pair of polisher elements hingedly connected, a bow spring member hingedly connected at each end to one of said polisher elements, the hinge connections of said bow spring member with said polisher elements being spaced equally from each other and from the hinge whereby said polisher elements are connected, and means associated with said bow spring member whereby the tension therein may be adjusted.

20. The method of generating polished curved surfaces on ground lens blanks mounted in multiple on a spherical carrier, comprising the steps of rotating and oscillating a spherical carrier on its polar axis, and rotating and oscillating on its polar axis a polisher unit adapted and arranged to embrace the spherical carrier for the purpose of causing said polisher unit to operate effec- 17 tlvely on ground surfaces of lens blanks mounted in multiple on said spherical carrier.

21. The equatorial method of generating polished curved surfaces on lens blanks mounted in multiple on a spherical carrier, comprising the steps of actuating a spherical carrier rotatively while journaled in a, cradle, and actuating for combined rotation and oscillation about its polar axis, a hollow spherically formed polisher unit surrounding the spherical carrier at right angles to its equator, for the purpose of causing the polisher unit to operate effectively on the ground surfaces of lens blanks mounted in multiple on the spherical carrier.

22. The equatorial method of polishing spherical surfaces on ground lens blanks mounted in spherical formation on a carrier, comprising the steps of actuating a carrier for combined rotation and oscillation about the polar axis of the spherical formation of lens blanks, and actuating a hollow spherically formed polisher unit rotatively as it surrounds, rests upon and is supported by the spherical formation of lens blanks at right angles to the equator thereof, for the purpose of causing the polisher unit to generate true sph-erical surfaces on all lens blanks mounted on the carrier.

23. The equatorial method of polishing toric surfaces on several ground lens blanks mounted in spherical formation on a carrier, comprising oscillation about its principal axis, the inner 7,.

periphery of the ring polisher being somewhat greater in diameter than the spherical formation of lens blanks and contacting ground toric surfaces on lens blanks along arcs lying substantially in planes containing the polar axis of the spherical formation, for the purpose of causing the ring polisher to operate effectively on the ground toric surfaces of all lens blanks mounted on the carrier.

24. The equatorial generator method of polishing lens blanks mounted in multiple in spherical formation on a carrier and previously finish ground in an equatorial diamond milling generator, comprising the steps of actuating the carrier for combined rotation and oscillation about the polar axis of the spherical formation of lens blanks, and actuating, for combined rotation and oscillation, a hollow spherically formed polisher unit encircling the spherical formation of lens blanks so its equator moves over polar great circles thereon, for the purpose of polishing true and identical curved surfaces on all lens blanks mounted on the carrier.

ARTHUR J. HOLMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,221,858 Hollands Apr. 10, 1917 1,448,239 Schuessler Mar. 13, 1923 1,827,748 Holman Oct. 20, 1931 1,979,489 Priest Nov. 6, 1934 2,257,452 Binns et a1. Sept. 30, 1941 2,307,238 Ross Jan. 5, 1943 FOREIGN PATENTS Number Country Date 6,978 Great Britain May 12, 1894 249,094 Great Britain Jan. 6, 1927 

